4.4BSD/usr/share/man/cat2/sigprocmask.0

SIGPROCMASK(2)              BSD Programmer's Manual             SIGPROCMASK(2)

NNAAMMEE
     ssiiggpprrooccmmaasskk - manipulate current signal mask

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<ssiiggnnaall..hh>>

     _i_n_t
     ssiiggpprrooccmmaasskk(_i_n_t _h_o_w, _c_o_n_s_t _s_i_g_s_e_t___t _*_s_e_t, _s_i_g_s_e_t___t _*_o_s_e_t);

     ssiiggmmaasskk(_s_i_g_n_u_m);

DDEESSCCRRIIPPTTIIOONN
     The ssiiggpprrooccmmaasskk() function examines and/or changes the current signal
     mask (those signals that are blocked from delivery).  Signals are blocked
     if they are members of the current signal mask set.

     If _s_e_t is not null, the action of ssiiggpprrooccmmaasskk() depends on the value of
     the parameter _h_o_w. The signal mask is changed as a function of the speci-
     fied _s_e_t and the current mask.  The function is specified by _h_o_w using
     one of the following values from <_s_i_g_n_a_l_._h>:

     SIG_BLOCK    The new mask is the union of the current mask and the speci-
                  fied _s_e_t.

     SIG_UNBLOCK  The new mask is the intersection of the current mask and the
                  complement of the specified _s_e_t.

     SIG_SETMASK  The current mask is replaced by the specified _s_e_t.

     If _o_s_e_t is not null, it is set to the previous value of the signal mask.
     When _s_e_t is null, the value of _h_o_w is insignificant and the mask remains
     unset providing a way to examine the signal mask without modification.

     The system quietly disallows SIGKILL or SIGSTOP to be blocked.

RREETTUURRNN VVAALLUUEESS
     A 0 value indicated that the call succeeded.  A -1 return value indicates
     an error occurred and _e_r_r_n_o is set to indicated the reason.

EERRRROORRSS
     The ssiiggpprrooccmmaasskk() call will fail and the signal mask will be unchanged if
     one of the following occurs:

     [EINVAL]      _h_o_w has a value other than those listed here.

SSEEEE AALLSSOO
     kill(2),  sigaction(2),  sigsetops(3),  sigsuspend(2)

SSTTAANNDDAARRDDSS
     The ssiiggpprrooccmmaasskk function call is expected to conform to IEEE
     Std1003.1-1988 (``POSIX'').

4.4BSD                           June 4, 1993                                1